Marc Faber says the stock market is setting up for a decline more painful than the sudden crash of 1987.

"I think it's very likely that we're seeing, in the next 12 months, an '87-type of crash," Faber said with a devious chuckle on Thursday's episode of "Futures Now." "And I suspect it will be even worse."

Faber, the editor and publisher of the Gloom, Boom & Doom Report, has recently called for growth stocks to decline. And he says the pain in the Internet and biotech sectors is just getting started.

"I think there are some groups of stocks that are highly vulnerable because they're in cuckoo land in terms of valuations," Faber said. "They have no earnings. They're valued at price-to-sales. And this is not a good metric in the long run."

To be sure, there are prominent investors that disagree with Faber, among them legendary stockpicker Bill Miller, who said this week that conditions for a bad market simply don't exist.

But it's not just momentum stocks that Faber is wary of. He says that investors are coming to a stark realization.

"I believe that the market is slowly waking up to the fact that the Federal Reserve is a clueless organization," Faber said. "They have no idea what they're doing. And so the confidence level of investors is diminishing, in my view."

Adam Jeffery | CNBC

Marc Faber

As investors adjust to this fact, and valuations shrink, he predicts a massive decline in the market.

"This year, for sure—maybe from a higher diving board—the S&P will drop 20 percent," Faber said, adding: "I think, rather, 30 percent. Who knows. But all I'm saying is that it's not a very good time, right now, to buy stocks."

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